Flaw detection fluid and method for detecting flaws in solid surfaces



U.S. Cl. 250--71 8 Claims ABSTRACT OF THE DISCLOSURE A flaw detection fluid for detecting flaws in solid surfaces comprising a solution of a water insoluble dye in a mixture of trimethylnonanol adduct having 6 mols of ethylene oxide and a water and oil soluble liquid hydroxy ether.

The present invention is directed to a flaw detection fluid and method for detecting flaws in solid surfaces. By solid surface, as used herein, is meant the surface of any non-porous solid, such as a non-porous plastic, glass, porcelain, ceramic, or metal.

This application is a continuation-in-part of my patent application Ser. No. 504,178 filed Oct. 23, 1965, now abandoned.

Flaw detection fluids have been widely used for the detection of flaws, cracks and imperfections extending inwardly from the surface of bodies. Examples of such fluids are set forth in Patents 2,478,951 issued Aug. 16, 1949, and 2,806,959 issued Sept. 17, 1957.

Conventional flaw detecting methods involving the use of a flaw detection fluid involve the spraying or dipping of the non-porous solid surface with the flaw detection fluids, followed by the removal of the flaw detection fluid. The flaw detection fluid may be removed by water washing, removal by the use of a solvent, or by emulsification techniques. Water washing is preferable because of its speed and ease. However, until the advent of the present invention, the use of Water washing techniques has not proved entirely satisfactory since the water washing will tend to remove the flaw detection fluid from cracks and in particular wide cracks.

The use of emulsiflcation and post-emulsification techniques is not altogether satisfactory. Thus, the use of such techniques is time consuming, and requires careful application. Moreover, such techniques may lead to errors due to the emulsification and removal of flaw detection fluids from cracks in the solid surface.

Following the removal of the flaw detection fluid from the surface that is being examined, the cracks can be located. This can be accomplished in the case of a nonfluorescent dye by visual examination. In the case of a fluorescent dye, the location of the cracks containing the flaw detection fluid can be accomplished by exposure to black light.

In addition, a wide variety of so-called developing techniques can also be used in which very finely divided powder, such as talc, calcium carbonate, or diatomaceous earth is applied to the surface, and removed. Such powder tends to act as a focus for the dye in the flaw detection fluid retained within cracks in the metal surface.

The great majority of the flaw detection fluids used in the field have comprised hydrocarbonor chlorinated hydrocarbon solvents. These preparations suffer from the handicap of having a flash point and flammability problem in the case of those comprising a hydrocarbon solvent, and a toxicity problem in the case of those comprising a chlorinated hydrocarbon.

3,456,110 Patented July 15, 1969 My application Ser. No. 504,178 filed Oct. 23, 1965, of which the subject application is a continuation-inpart, disclosed a superior flaw detection fluid and method for detecting flaws in metal surfaces which overcame many of the difliculties of the prior art.

However, I have now discovered that the invention of my patent application Ser. No. 504,178 can be improved by the invention of the subject application.

This invention has as an object the provision of a novel flaw detection fluid.

This invention has as another object the provision of a flaw detection fluid having superior penetrating properties.

This invention has as still another object the provision of a flaw detecting fluid which may be safely stored and handled.

This invention has as still a further object the provision of a method for detecting flaws in metal surfaces using a flaw detection fluid in which water Washing may be used subsequent to the spraying or dipping of the metal surface to be treated, and yet which will detect very fine cracks in the metal surface.

This invention has as a yet further object the provision of a method for detecting flaws in metal surfaces which can be rapidly accomplished without the use of skilled technicians.

Other objects will appear hereinafter.

The flaw detection fluids of the present invention can be used with any solid non-porous surface, such as metal, plastic, glass, porcelain, or ceramic surfaces in which surface cracks are possible.

In its broadest aspects, the flaw detection fluid of the present invention comprises a solution of from 0.2 to 6.0 weight percent of a water-insoluble dye; and a liquid organic compound capable of dissolving said dye and which organic compound is at least 20 weight percent soluble in water, and a surfactant which is at least appreciably soluble, such as at least 20 Weight percent, in said organic compound. The ratio of liquid organic compound to surfactant may vary from 1 to 99 volume percent of the liquid organic compound to 99 to 1 volume percent of the surfactant. Preferably, the ratio should be from to 20 volume percent of the liquid organic compound to 20 to 80 volume percent of the surfactant.

Examples of suitable liquid organic compounds capable of dissolving water-insoluble dyes which are at least 20 weight percent soluble in water include: hydroxy-ethers which are waterand oil-soluble, such as 2-butoxyethanol; Z-methoxyethanol; 2-ethoxyethanol; 2-(2-methoxyethoxy) ethanol; diethylene glycol ethyl ether; diethylene glycol n-butyl ether; propylene glycol methyl ether; dipropylene glycol methyl ether; tripropylene glycol methyl ether; 2-n-propoxyethanol; and 2-isopropoxyethanol; octyl phenol ethylene oxide condensates which are both Waterand oil-soluble; nonyl phenol ethylene oxide condensates which are both waterand oil-soluble; ethoxylated linear alcohols; aliphatic monohydroxy and dihydroxy alcohols which are at least 20 weight percent soluble in water and capable of dissolving the water-insoluble dye which is used; sulfonated oils, such as sulfonated castor oil, soya oil, rapeseed oil, tall oil, etc. The chemical nature of the organic compound is not critical, provided that it is capable of both dissolving the dye and at least appreciably dissolving the surfactant.

A wide variety of surfactants may be used, particularly where the water soluble organic compound capable of dissolving the dye and which is at least 20% soluble in water is not in and of itself a surfactant. Examples of suitable surfactants include: liquid Spans such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, and sorbitan trioleate; T weens such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan trioleate; Renex surfactants which are polyoxyethylene esters of mixed fatty and resin acids; Tergitols, Triton type surfactants; Dowfax type surfactants; Pluronic type surfactants; an alkyl phenoxy polyethoxyethanol containing 6 to 18 carbon atoms in the alkyl groups and 4 to 30 mols of ethylene oxide per mol of phenol, namely:

where R has from 6 to 18 carbon atoms and n is from 4 to 30; an alkyl ether of polyethylene glycol containing 1-18 carbon atoms in the alkyl groups and 2-20 oxyethylene groups; an amine condensate from the group consisting of mono, di, and triethanolamine, and isopropanolamine condensed with fatty acids, such as coconut, lauric, myristic, and tall oil fatty acids; a sodium salt of the sulfonated condensation product of naphthalene and formaldehyde; a water soluble sodium ligno sulfonates; an isopropyl naphthalene sulfonate; a sodium, potassium, calcium and ammonium salt of sulfated linear alcohols with a chain length of C C a sulfonated oil from the group consisting of the sulfonated castor, soya, rapeseed oils; and a pluronic such as The flaw detection fluid of the present invention may be dissolved, if desired, in miscible solvents. Thus, this invention comprehends the use of dilute solutions of the flaw detection fluid, although, normally in most cases, no useful purpose is served by the presence of such additional solvents. However, for specific applications where the solvent action of the additional solvent is desired, the additional solvent may be present, such as up to the order of about weight percent of the mixture of liquid organic compound and surfactant.

Any suitable Water-insoluble flaw detection fluid dye which is soluble in the liquid organic compound and surfactant may be used in the present invention. The concentration of the dye should be such as will enable the mixture to serve as a flaw detection fluid. Generally, this will be within the range of 0.2 to 6.0 weight percent. In the case of fluorescent dyes, most frequently this will be within the range of 0.2 to 1.0 weight percent. In the case of non-fluorescent dyes, this concentration will most frequently be of the order of 1 to 6 weight percent.

Examples of water-insoluble fluorescent dyes suitable for use in the present invention include Fluorol 7GA, a fluorescent dye made by General Dyestuffs Corporation; and water-insoluble fluorescent dyes within the following commercially available dyes: the Lumigraphic pigments produced by Hercules Powder Company, Imperial Color and Chemical Department, Glenn Falls, N.Y.; the Hi-Viz pigments produced by Lawter Chemicals, Inc.; the Velva-Glo pigments produced by Radiant Color Company of Richmond, Calif; and the Day-G10 pigments produced by Switzer Brothers, Inc., of Cleveland, Ohio; Resoform Fluorescent Yellow 102001 of General Aniline & Film Corporation. The nature of suitable Waterinsoluble fluorescent dyes (both fluorescent in daylight and in black light) is well known to those having ordinary skill in the chemical arts, and the specific nature of the dye forms no part of the present invention. There is a disclosure of a large number of these dyes in the article entitled Fluorescent Pigments in Kirk-Othmer, Encyclopedia of Chemical Technology, Second Edition, volume 9, pages 483 et seq.

Examples of suitable water-insoluble non-fluorescent dyes which may be used in the present invention include any of the water-insoluble dyes which have been used for flaw detection. A large number of Water-insoluble non-fluorescent dyes have been used for flaw detection, and the exact nature of these dyes form no part of the present invention. Examples include the following made by General Aniline & Film Corporation: Bismark Brown TSS Base; Chrysoidine Y Base; Sudan Corinth 3B; Sudan Black BR; Sudan Deep Black BN; Victoria Green Base; Induline Base B, etc.

Fluorescent dyes are preferred, and in particular, those that can be rendered more strongly visible by inspection under black light. To enhance the fluorescent properties of the fluorescent dye, it is preferred, though not essential, that a brightener be present. The use of brighteners for enhancing the fluorescent properties of the fluorescent dye is well known in the art. A suitable brightener is fluoranthene. Generally, the fluoranthene should be present in a concentration of 1 to 6 weight percent, although its concentration will vary depending on the nature of the dye and solvent in the composition. By way of example, a preferred weight percent concentration for Resoform Fluorescent Yellow 1'O2001 is between about 0.5 to 1.0 weight percent, most preferably about 0.8 weight percent. For this concentration, a fluoranthene concentration of between about 1.5 to 2.0 weight percent is suitable.

The preferred compositions of the present invention consist essentially of a water-insoluble fluorescent dye; a trimethylnonanol adduct having 6 mols of ethylene oxide; and a h ydroxy-ether. In these preferred compositions, the mixture of trimethylnonanol adduct and of hydroxy-ether may comprise any ratio between 1 volume percent of trimethylnonanol adduct to 99 volume percent of the hydroxy-ether and 99 volume percent of trimethylnonanol adduct to 1 volume percent of the hydroxyether. Preferably, the mixture should be within the range of 20 to volume percent of the trimethylnonanol adduct to 80 to 20 volume percent of the hydroxy-ether.

A wide variety of additives may be present in the composition of the present invention. Thus, suitable cleaner agents such as triethanolamine, concentrated liquid soaps, and the like, may be present in concentrations in which they are normally present in flaw detection fluids. In addition, rust removers and rust preventatives may be present, such as phosphoric acid type rust removers, in the concentrations normally present in flaw detection fluids.

In the method for detecting flaws in solid surfaces of the present invention, the flaw detection fluid is applied to the solid surface. This may be done manually, as by sprayin the surface with the flaw detection fluid, or the solid surface may be dipped into the flaw detection fluid. The flaw detection fluid is then removed by water Washing.

The flaws are readily detected by visual examination in daylight, or in the case of fluorescent dyes, with the aid of black light. Thus, I have found that using the compositions of the present invention with the method of the present invention, the contact between water and the flaw detection fluid in the crack in the solid surface results in precipitation of the dye in the crack. The nature of the precipitate will vary, and it is my belief that it frequently includes a portion or a derivative of the liquid organic compound.

The formation of the precipitate minimizes the risk of dislodgement from wide or shallow cracks.

The following examples of compositions of the present invention serve to illustrate the present invention.

Example 1 A solution of 49 weight precent of 2-butoxyethanol, 50 weight precent trimethylnonanol adduct having 6 mols of ethylene oxide, and 1 weight precent of Capracyl Red BP. This is a nonfluorescent flaw detection fluid. It may be applied to the surface for which cracks are sought, the excess may be removed by washing with water, and the cracks may be detected by the red dye disposed within the cracks. If desired, a so-called development technique can be use. Thus, a finely divided powder, such as diatomaceous earth may be sprinkled on the surface, and then the powder removed. The powder will serve to enhance the present of the dye and facilitate the location of cracks.

Example 2 A fluorescent composition comprising 54 weight percent 2-butoxyethanol, 43 /2 weight percent of the trimethylnonanol adduct having 6 mols of ethylene oxide, V2 weight percent of Fluorol 5G, and 2 weight percent of fluoranthene. This composition is fluorescent. The metal part to be examined may be dipped or sprayed with the composition. The spray or dip is then removed by water washing. The cracks can be detected by exposing the metal part to the action of black light. If desired, the use of a developing technique, such as the use of a finely divided talc may be used as in Example 1.

Example 3 A solution of 35 weight percent 2-butoxyethanol, 62 weight percent of the trimethylnonanol adduct having 6 mols of ethylene oxide, 1 weight percent 2-7-dimethyl coeroxen, and 2 weight percent of fluoranthene.

Example 4 A solution of 35 weight percent Z-butoxyethanol, 50 weight percent of the trimethylnonanol adduct having 6 mols of ethylene oxide, weight percent of triethanolamine, 3 weight percent of Azosol Yellow 6GP, and 2 weight percent of fluoranthene.

Example 5 A solution of 90 weight percent 2-ethoxyethanol, 7 weight percent of the trimethylnonanol adduct having 6 mols of ethylene oxide, and 3 weight percent of brilliant sulfoflavine FFA.

Example 6 A solution comprising 18 weight percent of 2-methoxyethanol, 75 weight percent of the trimethylnonanol adduct having 6 mols of ethylene oxide, 2 Weight percent of Anthraquinone Red MR, and 5 weight percent of triethanolamine.

Example 7 A solution of 60 Weight percent of sulfonated castor oil, 37 weight percent of sorbintan monopalmitate, and 3 weight percent of Resoform Fluorescent Yellow 10- 2001.

Example 8 A solution of 45 weight percent of a waterand oil-insoluble octyl phenol ethylene oxide condensate, 54 weight percent of a Renex surfactant, and 1 weight percent of Sudan Orange RA.

Example 9 A solution comprising 77 weight percent of isopropyl alcohol, 22 /2 weight percent of sorbitan tristereate, and 0.5 weight percent of Fluorol 7GA.

Example 10 A solution of weight percent glycol, 84.2 weight percent of sorbitan monolaurate, and 0.8 weight percent of methyl violet base A.

Example 11 A solution consisting essentially of 36 weight percent sulfonated rapeseed oil, 53.7 weight percent of trimethylnonanol adduct having 6 mols of ethylene oxide, and 0.3 weight percent of Resoform Fluorescent Yellow 10-2001.

By solution as used herein is meant true clear solutions, and also mixtures in which a major portion of the components are dissolved but in which the non-dissolved portion is suspended in a finely divided dispersed state.

The flaw detection fluids of the present invention are most efficient and dependable, and minimize the risk of dislodgement from wide or shallow cracks, which is present in prior techniques.

I have also found that the flaw detection fluids of the present invention have excellent penetrating properties, even into metal surfaces that are soiled by hydrocarbons, dirts, earths, etc.

The flaw detection fluids of the present invention do not turn milky or hazy upon contamination with water as is frequently the case with conventional flaw detection fluids, and particularly those which contain emulsifying agents. Moreover, the formation of gels or scums is almost entirely absent with the flaw detection fluids of the present invention.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

It is claimed:

1. A flaw detection fluid for detecting flaws in solid surfaces consisting essentially of a solution of from 0.2 to 6.0 weight percent of a water-insoluble dye in a mixture of trimethylnonanol adduct having 6 mols of ethylene oxide and a waterand oil-soluble liquid hydroxyether, with the ratio of trimethylnonanol adduct to the hydroxy-ether being between 1 to 99 volume percent of the trimethylnonanol adduct to 99 to 1 volume percent of the hydroxy-ether.

2. A flaw detection fluid in accordance with claim 1 in which the ratio of the trimethylnonanol adduct to the hydroxy-ether is between 20 to volume percent of the trimethylnonanol adduct to 80 to 20 volume percent of the hydroxy-ether.

3. A flaw detection fluid in accordance with claim 2 in which the dye is a fluorescent dye which is present within the range of 0.2 to 1.0 weight percent.

4. A flaw detection fluid in accordance with claim 2 in which the dye is a non-fluorescent dye which is present within the range of 1 to 6 weight percent.

5. A flaw detection fluid in accordance with claim 3 in which the fluid includes a brightener.

6. A method for detecting flaws in solid surfaces comprising applying the flaw detection fluid of claim 1 to a solid surface, removing excess flaw detection fluid by washing the metal surface with water to form a precipitate containing the dye in the flaw, and detecting the flaw in the solid surface by visibly observing the dye.

7. A method for detecting flaws in solid surfaces comprising applying the flaw detection fluid of claim 3 to a solid surface, removing excess flaw detection fluid by Washing the metal surface with water to form a precipitate containing the dye in the flaw, and detecting the flaw in the solid surface by visibly observing the dye while the solid surface is exposed to black light.

8. A method for detecting flaws in solid surfaces comprising applying the flaw detection fluid of claim 1 to a solid surface, removing excess flaw detection fluid by Washing the metal surface with water to form a precipitate containing the dye in the flaw, and detecting the flaw in the solid surface by visibly observing the dye.

References Cited UNITED STATES PATENTS 3,311,479 3/1967 Alburger 25230l.2

FOREIGN PATENTS 719,445 1/1954 Great Britain.

TOBIAS E. LEVOW, Primary Examiner I. COOPER, Assistant Examiner US. Cl. X.R. 

